My name is Sunny Zhang and I am a rising sophomore at the University of Pennsylvania studying physics. Although I have never done research in environmental science prior to coming to Penn, I was involved in energy research for many years in high school and was also an active member of environmental groups. This summer, I had the opportunity to pursue my interest in materials science research while also learning about various applications to biosensing and environmental health. Participating in the STEER program has introduced me to many new fields which I can now add to my list of possible future research directions.
What is your summer research project?
This summer, I have been working in the lab of Dr. Charlie Johnson. My research project involves biosensors in the form of highly sensitive carbon nanotube field-effect transistors (NTFETs) as a way to detect environmental toxins. Specifically, I decided to focus on the detection of benzene, which is a known pollutant in air and groundwater. To do this, I used an olfaction system based on large arrays of NTFET sensors to detect volatile organic compounds (VOCs) in the headspace of samples prepared with varying concentrations of benzene. The arrays were functionalized with single-stranded DNA (ssDNA), each with a particular sequence that interacts with the VOCs (in this case the benzene vapor). By measuring the current responses of each device when exposed to the benzene vapor, I was able to distinguish the various concentrations of benzene in the original samples.
What are the implications of your research?
According to the World Health Organization, human exposure to benzene has been associated with various adverse health effects, including cancer and anemia. Toluene, ethylbenzene, and xylene are also similarly harmful, and all of these chemicals are widely used in the petroleum industry. Because the electronic olfaction system is modeled after mammalian olfaction systems, it contains many sensors that each respond differently to aromatic molecules, meaning that the system can be used to detect a wide variety of VOCs. In addition to benzene, it has been able to detect low concentrations of dinitrotoluene (DNT) and dimethyl methylphosphonate (DMMP), among other chemicals. In the future, we can test for certain metabolites resulting from exposure to organic pollutants, since the system is also capable of detecting and identifying volatile biomarkers for various diseases.
What new skills have you gained through this experience?
Over the course of the summer, I have gained many new skills both in and out of the lab. In my research, I was introduced to nanofabrication techniques such as ALD and PVD. I also learned how to handle organic chemicals and biological material. In addition, the weekly lectures and field trips helped me learn about research techniques in many different fields, ranging from laboratory experiments to case studies to community-based approaches. I learned that in some cases, environmental science research is not limited to a lab. For instance, in the town of Palmerton, the scientists at the Lehigh Gap Nature Center had the entire town and mountainside to work with, and the process of treating the environmental damage was an endeavor that took years, rather than a project that could be completed over the course of a summer. Overall, my experience with the STEER program has been both challenging and rewarding, and I am very grateful to have had this opportunity this summer.